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1-1.
SECTION
1
OUTLINE
SERVO
CONTROL
CIRCUIT
OPERATION
Stage/Control
Frequency
generator (FG)
Discriminator
Q101
Function
This generator is coaxially cou-
pled with dc motor.
The
frequency
of FG varies in
direct proportion
to the motor
rotation.
Active high-pass filter consisting
of
Q101,
C101,
C102,
R103,
R104
and
R108
discriminates
the
output
of
FG.
When
the
input
frequency
in-
creases,
the output
of the dis-
criminator increases, or vice versa.
filter
A
output (V)
Ay
to)
NZ
|
I
|
440 Hz
re:
frequency {Hz}
Fig. 1-1.
Filter characteristics
Stage/Control
Speed control
R101
filter
output (V)
Function
This control shifts the filter char-
acteristics.
Fig. 1-2.
Voltage stabilizer
D101
Rectifier
D102, D103
Direct coupled
dc amplifier
Qi02, Q103,
Q104
frequency (Hz)
Shift of filter characteristics
This diode stabilizes B+ voltage
for Q101 and Q102.
These diodes rectify the output
of the discriminator as a voltage
doubler.
This amplifier amplifies dc com-
ponent
rectified
by
D102
and
D103
to control the motor cur-
rent. Since the output from FG
is not available when starting the
motor,
no dc component
is ap-
plied to QI02 base to turn Q102
off. Since Q103
base voltage is
high as
B+ voltage,
Q103
and
Q104 are conductive to start the
motor.
Qing, 103, 194
Be AME
+) B
Cig
C192
—
R103
Fig. 1-3.
Outline of servo control circuit
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